DESCRIPTION: This research is designed to examine the influence of structured mental representation on human performance. The study of structured mental representation investigates how propositional and relational information is stored and processed by the human cognitive system. The study of human performance investigates what factors in task influence peoples? speed and accuracy when carrying out that task. Typically, these two areas of inquiry are completely separate, both empirically and theoretically. As a result, current models of human performance ignore structured (propositional and relational) information about tasks, and cannot account for the influence of such information on human performance. The main goal of this research is to build empirical and theoretical bridges between these two areas of inquiry. Empirically, this research uses the choice reaction time (CRT) paradigm to investigate various ways in which the relational structures of the stimulus and response sets in a task influence performance, e.g.: can analogies between stimuli and responses give rise to compatibility? Do task demands bias the mental representation of relational structure? How does the influence of relational structure on similarity translate into influence on performance? Theoretically, this research examines ways in which connectionist models of structured information can be incorporated with models of performance, in order to account for these predicted effects, and others in the literature.